The present invention relates to a subscriber terminal of an interactive communication system, which includes a recording and reproducing apparatus for recording and reproducing a video signal transmitted, according to a request of the subscriber terminal, from a video software supplier, and, particularly, to a control method and apparatus for controlling a recording and reproducing operation of the recording and reproducing apparatus for a video signal transmitted from the software supplier through a suitable interactive transmission line such as coaxial cable, optical cable, telephone line or satellite broadcasting to a subscriber terminal.
A device for receiving and storing a transmitted compressed video signal is disclosed in, for example, Japanese Patent Application Laid-open No. H4-79588.
In the conventional technique disclosed in this article, a video signal is time-compressed and transmitted. In a receiver, the compressed video signal is recorded on a suitable recording medium by a video signal recording and reproducing apparatus such as video tape recorder (VTR) and the compressed video signal read out from the recording medium is time-axis decompressed and displayed. The recording may be performed automatically.
Although, in a conventional digital magnetic recording and reproducing apparatus such as VTR of D2 format, it is possible to increase or decrease a reproducing time by means of a variable reproduction speed system without degradation of image quality, it has been usual that a dubbing of a software of a certain time length takes the same time length as recording time of the software. According to the disclosed technique, the dubbing can be done within a shorter time due to employment of the time axis compression of the video signal. That is, in the disclosed technique, a video signal and audio signal are time-axis compressed to 1/m to reduce a transmitting time to 1/m and bit-compressed to 1/n to reduce a signal frequency band to m/n, where m and n are positive integers. Then, the compressed video and audio signals are attached with parity signals, modulated to a code suitable for a transmission line to be used and transmitted. The transmitted signals are received, demodulated and recorded at high speed by a recording and reproducing apparatus. The high speed recorded signals are reproduced at a normal speed and demodulated while correcting any error in the reproduced signals by using the parity signal. Then, the error corrected signals are bit-expanded and displayed. Therefore, the software can be recorded at higher speed using the same format as that used in the standard speed recording. However, the disclosed technique requires a relatively complicated circuit construction and relatively complicated operation.